jgit/org.eclipse.jgit/src/org/eclipse/jgit/util/IntList.java

/*
 * Copyright (C) 2008, Google Inc.
 * Copyright (C) 2009, Johannes Schindelin <johannes.schindelin@gmx.de>
 * and other copyright owners as documented in the project's IP log.
 *
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
 * accompanies this distribution, is reproduced below, and is
 * available at http://www.eclipse.org/org/documents/edl-v10.php
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials provided
 *   with the distribution.
 *
 * - Neither the name of the Eclipse Foundation, Inc. nor the
 *   names of its contributors may be used to endorse or promote
 *   products derived from this software without specific prior
 *   written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.eclipse.jgit.util;

/** A more efficient List&lt;Integer&gt; using a primitive integer array. */
public class IntList {
	private int[] entries;

	private int count;

	/** Create an empty list with a default capacity. */
	public IntList() {
		this(10);
	}

	/**
	 * Create an empty list with the specified capacity.
	 *
	 * @param capacity
	 *            number of entries the list can initially hold.
	 */
	public IntList(final int capacity) {
		entries = new int[capacity];
	}

	/** @return number of entries in this list */
	public int size() {
		return count;
	}

	/**
	 * @param i
	 *            index to read, must be in the range [0, {@link #size()}).
	 * @return the number at the specified index
	 * @throws ArrayIndexOutOfBoundsException
	 *             the index outside the valid range
	 */
	public int get(final int i) {
		if (count <= i)
			throw new ArrayIndexOutOfBoundsException(i);
		return entries[i];
	}

	/** Empty this list */
	public void clear() {
		count = 0;
	}

	/**
	 * Add an entry to the end of the list.
	 *
	 * @param n
	 *            the number to add.
	 */
	public void add(final int n) {
		if (count == entries.length)
			grow();
		entries[count++] = n;
	}

	/**
	 * Assign an entry in the list.
	 *
	 * @param index
	 *            index to set, must be in the range [0, {@link #size()}).
	 * @param n
	 *            value to store at the position.
	 */
	public void set(final int index, final int n) {
		if (count < index)
			throw new ArrayIndexOutOfBoundsException(index);
		else if (count == index)
			add(n);
		else
			entries[index] = n;
	}

	/**
	 * Pad the list with entries.
	 *
	 * @param toIndex
	 *            index position to stop filling at. 0 inserts no filler. 1
	 *            ensures the list has a size of 1, adding <code>val</code> if
	 *            the list is currently empty.
	 * @param val
	 *            value to insert into padded positions.
	 */
	public void fillTo(int toIndex, final int val) {
		while (count < toIndex)
			add(val);
	}

	private void grow() {
		final int[] n = new int[(entries.length + 16) * 3 / 2];
		System.arraycopy(entries, 0, n, 0, count);
		entries = n;
	}

	public String toString() {
		final StringBuilder r = new StringBuilder();
		r.append('[');
		for (int i = 0; i < count; i++) {
			if (i > 0)
				r.append(", "); //$NON-NLS-1$
			r.append(entries[i]);
		}
		r.append(']');
		return r.toString();
	}
}